From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f52.google.com (mail-pj1-f52.google.com [209.85.216.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6190F10E9 for ; Tue, 24 Jan 2023 16:32:55 +0000 (UTC) Received: by mail-pj1-f52.google.com with SMTP id z1-20020a17090a66c100b00226f05b9595so14569358pjl.0 for ; Tue, 24 Jan 2023 08:32:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=WEjR3MMUrHfbjILuF7dobsrFdV5OhfxF21ZQLpjye7U=; b=oZ0G5N/t1eDXjYcoYiwY41LK0h5eGp3QsK5+D174rof58LylqVRvhMnP8mIJ0k9PAe GdcwzYKSVwF4U40oMXci76lh80JgrM+5/pdmAMQj414mN4QzlvrKrFhsigFiVVt2Dwco wXxPItYsjXE81AWKqcMStZ87lo4OMt5lKkNfjUOSD8yguvFbE6lD7Fev2F6BmPCg55s9 I2XCcZNRTTpzkV2z4TSSin/2KswPs9EXw3wsGvonMxbpyIieZaXhXxkJG6PJ9cpfa43I 1lz1uFK7g5irexIQBYpZmszKSK78r79GCPiNIG1xJeIOQD/ZrnfGNOtk6jVzZmzEXBbO b7uQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=WEjR3MMUrHfbjILuF7dobsrFdV5OhfxF21ZQLpjye7U=; b=JH9B61zK4H63QpyxWFt/pMr2UX+/HYFK6l9NLzVaZtQbBeaJWyW3aBw7yPRvMMkB8f /d2zobu3O0RVCNvHkgLbkoJs0uQwUrKMYzhNm4KubMOf4KL964h1cpuHSYhG2ZKw1rVw P8qQTZRGcRGZbjiy96PyT8HtH0n/t+tUQtHOZYRIH0AO3J8UIg+OjGU4OaSwjCin1OU4 4EVexvaxy3URf7YE9T9kSHuGpyrxaTGd51Cqp+F63BCrLd48OFwWCDEIT+gJnTU0iHFx z49RS3LDD1G9LYmLSzKwCCXTQm5kaoz5LoHnvLnkmb5T7MIMnPZr1/mCgY8gZLTc7OzB g2XA== X-Gm-Message-State: AO0yUKVhLCM5HpRj42c1T410TwuUCxKOZTEBjdXzPHCGQsuAfOU0pGY2 x+jWDZwZMe/Pm/XxQX5kTJEkJA== X-Google-Smtp-Source: AK7set/DWflTmlF2dzZZVpG42fRxvToZgU8UWyKHB2mCwB11kxSKJSfCxlOy7Dcft8FG9fYFxc9TAw== X-Received: by 2002:a17:90a:14e5:b0:229:1e87:365f with SMTP id k92-20020a17090a14e500b002291e87365fmr225584pja.2.1674577974493; Tue, 24 Jan 2023 08:32:54 -0800 (PST) Received: from google.com (220.181.82.34.bc.googleusercontent.com. [34.82.181.220]) by smtp.gmail.com with ESMTPSA id z88-20020a17090a6d6100b00229188a823dsm8672967pjj.20.2023.01.24.08.32.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 08:32:54 -0800 (PST) Date: Tue, 24 Jan 2023 08:32:50 -0800 From: Ricardo Koller To: Oliver Upton Cc: Ben Gardon , pbonzini@redhat.com, maz@kernel.org, yuzenghui@huawei.com, dmatlack@google.com, kvm@vger.kernel.org, kvmarm@lists.linux.dev, qperret@google.com, catalin.marinas@arm.com, andrew.jones@linux.dev, seanjc@google.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, eric.auger@redhat.com, gshan@redhat.com, reijiw@google.com, rananta@google.com, ricarkol@gmail.com Subject: Re: [PATCH 1/9] KVM: arm64: Add KVM_PGTABLE_WALK_REMOVED into ctx->flags Message-ID: References: <20230113035000.480021-1-ricarkol@google.com> <20230113035000.480021-2-ricarkol@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Jan 24, 2023 at 12:56:11AM +0000, Oliver Upton wrote: > On Mon, Jan 23, 2023 at 04:51:16PM -0800, Ben Gardon wrote: > > On Thu, Jan 12, 2023 at 7:50 PM Ricardo Koller wrote: > > > > > > Add a flag to kvm_pgtable_visit_ctx, KVM_PGTABLE_WALK_REMOVED, to > > > indicate that the walk is on a removed table not accesible to the HW > > > page-table walker. Then use it to avoid doing break-before-make or > > > performing CMOs (Cache Maintenance Operations) when mapping a removed > > > > Nit: Should this say unmapping? Or are we actually going to use this > > to map memory ? > > I think the *_REMOVED term feels weird as it relates to constructing a > page table. It'd be better if we instead added flags to describe the > operations we intend to elide (i.e. CMOs and TLBIs). What about KVM_PGTABLE_WALK_ELIDE_BBM and KVM_PGTABLE_WALK_ELIDE_CMO? > That way the > implementation is generic enough that we can repurpose it for other use > cases. Aha, good point. I actually have a use case for it (FEAT_BBM). > > -- > Thanks, > Oliver